`createFetchExecutor(baseURL, options?)` — `@routar/core`

Uses the native fetch API. Ideal for SSR where per-request dynamic headers are needed. Built into @routar/core — no additional package required.


import { createFetchExecutor } from '@routar/core'
 
const executor = createFetchExecutor('https://api.example.com')

Options


createFetchExecutor(baseURL, {
  defaultHeaders: async () => {
    const token = await getServerToken()
    return token ? { Authorization: `Bearer ${token}` } : {}
  },
  plugins: [logger()],
  retry: 2,
  timeout: 5_000,
})

Option	Type	Description
`defaultHeaders`	`() => Promise<Record<string, string>> \| Record<string, string>`	Applied to every request. Evaluated per-request, so safe for SSR token injection.
`plugins`	`ExecutorPlugin[]`	Plugins applied before the fetch call
`retry`	`number \| { count, shouldRetry? }`	Number of retries on failure
`timeout`	`number`	Per-attempt timeout in milliseconds — throws `TimeoutError` on expiry

Empty responses

Responses with status 204, 205, or 304 resolve to null. A 200 response with an empty body also resolves to null instead of throwing a SyntaxError.

`HttpError`

Non-2xx responses throw HttpError. The parsed JSON error payload is available on .body (or null if the body was empty or not JSON):


import { HttpError } from '@routar/core'
 
try {
  await todoApi.getDetail({ path: { id: 999 } })
} catch (err) {
  if (err instanceof HttpError) {
    console.log(err.status)     // 404
    console.log(err.statusText) // 'Not Found'
    console.log(err.body)       // { message: 'Not found' } | null
  }
}

Query parameter serialization

Arrays are serialized as repeated keys: ids=1&ids=2. This differs from Axios’s default (ids[]=1&ids[]=2). If you switch executors and use array query params, verify your server-side parsing is compatible.

SSR usage (Next.js)


import { createFetchExecutor } from '@routar/core'
 
export const serverExecutor = createFetchExecutor(process.env.API_BASE_URL!, {
  defaultHeaders: async () => {
    const { cookies } = await import('next/headers')
    const token = (await cookies()).get('access_token')?.value
    return token ? { Authorization: `Bearer ${token}` } : {}
  },
  timeout: 10_000,
})

defaultHeaders is called on every request, so it picks up the current request’s cookies in Server Components and Route Handlers.

createFetchExecutor(baseURL, options?) — @routar/core